Are the Cleaning Compounds (The Surfactants) in Laundry Detergents Really Safe to Use?

Because detergents contact our clothing, and clothing contacts our bodies, we are very open to the possibility of absorbing these substances through the skin. Cell membranes absorb electrically charged material selectively. Which is to say the cell must actively transport such materials across the cell membrane or these materials will not enter the cell. However, cell membranes will absorb oily, non-polar substances simply through contact. No active transport is needed. The long carbon tails of surfactant molecules ( the active agent in a detergent mix) are non polar. In fact they are very similar to the basic fatty acid molecules that make up cell membranes. Such materials are absorbed by cell membranes because of the mutual attraction of the fatty materials in the cell membranes and the surfactant molecule fatty acid carbon chains. In light of this, you might consider that the surfactants and other non-polar molecules which are part of detergent mixtures may constitute household toxins of an order much greater than we have ever considered. Just how likely are we to absorb the chemicals in detergents through our skin? And, how will these chemicals affect us? The surfactant sodium lauryl sulfate has been examined relative to this question.

It is of note that in experimental science, sodium lauryl sulfate - an anionic surfactant - has been demonstrated to serve as one of the most effective substances with which researchers might stimulate a sensitization reaction on the skin of an experimental subject. This is a procedure which is needed when testing the allergen properties of various substances on a living organism.

Studies on the actual interaction of anionic surfactants, at the cellular level reveals that when surfactants such as sodium lauryl sulfate are applied to the skin but then later washed off, not all of the surfactant is removed. These compounds adhere to the skin surface even after rinsing takes place. Further more, these substances do not merely adhere to the surface of the skin but in time penetrate it. Sodium lauryl sulfate was shown to denature proteins, extract compounds such as amino acids from the stratum dorneaum and to eventually penetrate the deeper layers, right into to the living cells. It has been observed, experimentally, that the removal of these substances from the structure of the skin gives rise to the sensation of a tightening of the skin’s surface (Gloxhuber,1992). It looks like the " feeling of clean" may actually be the " feeling of skin destruction".

Many so called "natural detergents", shampoos and personal cleansers use sodium lauryl sulfate as the primary surfactant in the mixture. Yet, is this a substance that we really should have in such close association with our bodies?

At the very least some caution should be warranted when using surfactants in the household and upon our bodies. The question of what the long term impact of detergent surfactants that rub off from our clean laundry onto the surface of our skin is needs to be taken into account. Choosing a good laundry cleaning agent is not such a simple matter perhaps as most people may have been lead to believe.

Anionic surfactants, the major cleaning agent in most laundry detergents, are not generally absorbed by inorganic solids. Cationic surfactants, on the other hand, are strongly absorbed by solids, particularly clays. There is also a significant degree of absorption of both anionic and non-ionic surfactants in activated sludge and organic river sediments (ukmarine.org.uk, 2001).

This means that the most commonly used surfactants in laundry detergents need to be decomposed in sewage treatment plants before they are released into the environment. If they are not decomposed before the treated water is released they will be found within the water supply since they will not be absorbed by natural surfaces in the water ways.

According to industry reports, the biodegradability of surfactants that are in modern day use are considered by the industry to be adequate when sewage is properly treated. Even so, these same reports state that a certain percentage of the anionic surfactant molecules will indeed pass through the sewage treatment process unchanged. These molecular toxins are being released into the environment every day from even the most efficiently run sewage treatment plants. These molecules are not necessarily benign in nature, and have all been shown to exhibit toxic effects at sufficient concentrations.

Also, surfactants which contain branched hydrophobes (long water repelling carbon chains) are not as easily biodegraded as the more common surfactants which contain simple linear hydrophobes. An example of a branched hydrophobe would be the cationic surfactant that is used as a fabric softener. A much larger proportion of these surfactants will be released into the environment from sewage treatment plants.

The nonionic surfactants nonylphenol and some of its ethoxylates are not degraded very easily during sewage treatment. The prime source of their presence in the environment arises form their incomplete degradation in sewage treatment plants (Mihaich, 2003). These surfactants have been banned by the EU, yet are still considered acceptable for use in the United States. In Europe the environmental toxicity of these substances has be demonstrated but industry scientists in the United States have painted a different picture. As a result, no restrictions on damage to our environment by these toxins have been brought to bear.

References:

Mihaich, E. et al; Relative Toxicity Ranking of Nonylphenol Ethoxylates and their Degradation Intermediates to Estimate Cumulative Hazards and Risks [Internet] Kansas City, MO: AOCS; May 7, 2003. Available from:(www.aperc.org. )

Ukmarine.org; UK Marine Special Areas of Conservation; Surfactants [Internet].UK Marine SACs Project, UK; 2001 Available from (http://www.ukmarinesac.org.uk/activities/water-quality/wq8_46.htm)

Ukmarine.org; UK Marine Special Areas of Conservation; Surfactants [Internet].UK Marine SACs Project, UK; 2001 Available from (http://www.ukmarinesac.org.uk/activities/water-quality/wq8_46.htm)

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